THE PROGESTIN CONTENT OF THE CORPUS LUTEUM OF THE SOW (SUS SCROFA) DURING SUCCESSIVE STAGES OF THE ESTROUS CYCLE AND PREGNANCY

Abstract

The corpora lutea contain appreciable amts. of progestin during the 1st 3 days after ovulation, before the corpus luteum cells are fully differentiated. During the estrous cycle the content rises until retrogression sets in at the 15th day, after which progestin cannot be detected. During pregnancy there is a further sharp rise until the 20th day. The progestin content remains high and apparently rises, even into the 4th month. A drop occurs some time toward the 105th day, and during the last 10 days (110-120th day) progestin is not found in the corpora lutea.